The present invention relates to selectively etching portions of a substrate, and more particularly, this invention relates to a system and method for controlling the differential etch rate difference between one or more materials of a substrate.
Techniques for etching substrates, such as microelectronic devices, magnetic heads, etc., are known in the art. Conventional etching processes include, for example, inert gas plasma sputtering, ion milling or reactive ion etching, etc. In these processes, etching occurs as a result of physical impingement of ions on the surface of the substrate to be etched, or as a result of interaction between the impingement ions and the etched surface, or both. However, only small differential etch rates have been achieved in these processes, by varying the impingement angle.